Photochromic compounds and materials, in response to certain wavelengths of electromagnetic radiation (or “actinic radiation”), typically undergo a transformation from one form or state to another form, with each form having a characteristic or distinguishable absorption spectrum associated therewith. Typically, upon exposure to actinic radiation, many photochromic materials are transformed from a closed-form, which corresponds to an unactivated (or bleached, or substantially colorless) state of the photochromic material, to an open-form, which corresponds to an activated (or colored) state of the photochromic material. In the absence of exposure to actinic radiation, such photochromic materials are reversibly transformed from the activated (or colored) state, back to the unactivated (or bleached) state. Compositions and articles, such as eyewear lenses, that contain photochromic materials or have photochromic materials applied thereto (such as in form of a photochromic coating composition) typically display colorless (or clear) and colored states that correspond to the colorless and colored states of the photochromic materials contained therein and/or applied thereto. Photochromic compounds and materials are typically characterized with regard to various properties, such as photochromic properties, which include, but are not limited to, fade rate, change in optical density (sometimes designated as ΔOD), and dichroic properties.
It would be desirable to develop new photochromic compounds. It would be further desirable that such newly developed photochromic compounds possess properties, such as photochromic properties, that are at least the same as or better than those of existing photochromic compounds.